Page 559 - Adams and Stashak's Lameness in Horses, 7th Edition

Lameness of the Distal Limb 525

of the PIP joint is larger, which makes surgical manipula- comminuted P2 fractures may be treated successfully
52
tion somewhat easier, but it is still difficult. Osteochondral using this approach, but cast application for a minimum
VetBooks.ir arthroscopy if possible.
of 8 weeks is usually required.
fractures involving the DIP joint are also best managed by
Eminence Fractures Prognosis
The prognosis of horses with osteochondral fractures
Uniaxial or biaxial eminence fractures of P2 that treated by arthrotomy or arthroscopy appears to be very
involve the PIP joint are best treated by arthrodesis of good for return to full serviceability. 46,52,60,70,72 In one
the PIP joint followed by cast application. 42 study 4 of 5 cases with osteochondral fragments (3
Although casting alone has been reported as an involved the PIP joint and 2 involved the DIP joint)
acceptable method of treatment in horses with uniaxial treated by arthrotomy returned to their intended use.
70
eminence fractures, it should be reserved for those cases There are only a few reports of using arthroscopy to
in which pasture or breeding soundness is desired and remove these fragments, but it is the preferred approach
economic constraints dictate this approach. The frac- with most horses returning to performance.
tures rarely heal back to the parent bone with casting The prognosis for uniaxial or biaxial palmar/plantar
alone, and secondary OA of the PIP joint leading to eminence fractures treated by arthrodesis also appears
chronic lameness is common. to be very good for return to performance and should be
Horses with biaxial eminence fractures will develop a considered similar to that expected for PIP joint arthro-
42
palmar/plantar subluxation of the PIP joint when casted desis used to treat OA of the joint. The use of single or
due to weight‐bearing forces pushing P1 distally. If inter- double bone plating is considered mandatory for biaxial
nal fixation of biaxial P2 fractures is not elected, then eminence fractures and will most likely improve the
transfixation pin casts or another type of external fixator prognosis of these horses returning to function. 12,42
is recommended over casting alone to maintain phalan- Horses with comminuted fractures that only involve
geal alignment. With either casting alone or transfixation the PIP joint usually have a good prognosis to return to
pin casts, the initial cost may be less to the owner, but the athletic performance, provided they are treated with
costs of repeat casting, prolonged confinement, compli- internal fixation. The prognosis for horses with biarticu-
cations, etc. are often not that much less or may be more lar comminuted P2 fractures is much reduced because
than what the cost of internal fixation would have been. the limiting factor in many cases is related to the health
Therefore, internal fixation of eminence fractures is the of the DIP joint. Older literature has stated that horses
preferred method of treatment. with comminuted biarticular P2 fractures have a 50%
survival rate and slightly greater than a 10% chance of
8
Comminuted P2 Fractures returning to athletic performance with casting alone.
This remains true today and emphasizes that horses
There are varying degrees of comminution associated with comminuted P2 fractures treated without internal
with nearly all P2 fractures, which can greatly affect treat- fixation are very unlikely to be athletically sound.
ment. In general, horses with comminuted P2 fractures Internal fixation with bone plates increases both sur-
should be reconstructed and repaired with some type of vival and return to athletic function in horses with com-
internal fixation (bone plating) if at all possible. Horses minuted P2 fractures. In one report 7 of 8 horses with
with an intact strut of bone spanning from the PIP to the forelimb involvement were alive 2 years after injury, and
DIP joints are ideal candidates for internal fixation. 4 of 7 horses were being ridden. Of the two horses with
Horses without an intact bony strut yet have large enough hindlimb involvement, one was being ridden and one
bony fragments for screw fixation also often benefit from was lost to follow‐up. In another report, 2 of 3 mature
10
internal fixation. Horses with highly comminuted P2 horses with comminuted fractures that involved the
fractures (so‐called bag of ice) that do not have fracture forelimbs returned to athletic performance, and 2 of 3 foals
fragments large enough to engage screws are best treated with physeal fractures also performed. 12
with transfixation pin casts or another type of external The prognosis of these horses is often dictated by the
fixator. 29,35,47,48 Casting alone can also be used for these amount of fracture displacement at the DIP joint and the
highly comminuted fractures, but fracture collapse would ability to reduce this displacement at the time of surgery.
be an expected complication. Horses with fractures of the hindlimb are also thought
The use of casts, transfixation pin casts, or an exter- to have an improved prognosis over those affecting the
nal fixator is usually reserved for horses with severely forelimb. In general, horses with biarticular comminuted
comminuted P2 fractures that cannot be adequately P2 fractures should be considered to have a 40–50%
reduced or stabilized by internal fixation and for which chance of returning to performance after internal fixa-
euthanasia is not an option. Economic constraints may tion, provided complications do not occur.
also enter into the decision regarding when to use these
options, although with the prolonged treatment period,
the difference in cost is often negligible. Pasture sound- FRACTURES OF THE PROXIMAL (FIRST)
ness for breeding purposes or use as a pet is all that can PHALANX (P1)
be expected from horses treated with casts with or with-
out transfixation pins. Traction to the phalanges using Fractures of the proximal phalanx (P1) occur fre-
wires placed through the hoof wall, especially in the quently and can be broadly categorized into noncommi-
hindlimb, helps reduce the fracture fragments. A lower nuted and comminuted fractures. Osteochondral
limb cast that incorporates the hoof is mandatory. Some fragmentations of the proximal dorsal or palmar/ plantar